I am trying to clean up a lighter color armrest, and the previous owner's nickname must have been Pigpen. It looks like this guy regularly worked on greasy car motors,and didn't wash up before driving home. So far, I have used dish soap, Gojo, Fast Orange, Resolve, and DuPont Interior Detailer on it, and have cut about half of it. Any ideas what to turn to next? Soak it in something? ... I did allow time for all of these products to sit and work.
If all the above fails, just re-dye them. Once that greasy black grime works its way into the vinyl it is very hard to completely get it out.
The safe way to clean vinyl without drying it out is with Leatherique Pristine clean http://www.leatherique.com/do_it_your_self_instruction/rejuvinator_pc_directions.html I'm doing a sports wheel and this stuff not only cleaned the steering wheel but made the wheel feel like new.
They got bad links on their page, I clicked on it, and it took me here: http://leatherique.org/detail.aspx?ID=36
Try No. 990 Auto Care Vinyl Leather Cleaner by Sprayway. Do a search on Google for it. A friend of mine who owned an upholstery shop for years turned me on to this stuff and it works great. It also has mink oil in it to keep everything nice and soft!